Molecular ribbons appear dim compared to Vive Pro ChimeraX VR

[tomgoddard]

Viewing the same scene of PDB 4hjv as ribbons with blue/purple default coloring with ChimeraX SteamVR in Vive Pro and Quest 2/Pro with LookSee shows much flatter dimmer colors in LookSee.

Part of the difference is the Vive Pro OLED displays have very dark black, while LookSee with show room off has a less dark black background due to its LCD panels. Another factor is the LookSee GLTF shaders are not showing specular highlights. But the main issue of this ticket is that the ribbon and stick side chains just are not as bright in LookSee.

[tomgoddard]

I enabled the UI canvas setting "Vertex color always in gamma color space" and this seemed to brighten the molecule. That does not make sense since that setting would appear to only effect the UI panels. I just compared visually before and after the change.

In Project Settings / Player / Rendering the Color Space setting is "linear" (not gamma). The Oculus XR plugin is documented to only support linear color space for lighting.

The GLTF spec defines the material colors to be in sRGB space (a mix of gamma ~2.2 near white and linear near black) and vertex colors to be in linear color space. ChimeraX is not using linear vertex colors. I think the current ChimeraX GLTF output converts ribbon vertex colors to a material color for single color ribbons.

The dimness may also be simply that the light intensity is a little too low.